Balloon Catheter

ABSTRACT

A balloon catheter includes an outer shaft, an inner shaft, and an inflatable balloon. The inner shaft is inserted inside the outer shaft. A part of the inner shaft extends from a leading end of the outer shaft. The balloon includes a base end side joint portion joined to the outer shaft and a leading end side joint portion joined to the inner shaft. The inner shaft has an extension portion configured to in an axial line direction. The extension portion is provided further to a base end side than the leading end side joint portion.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of International ApplicationNo. PCT/JP2015/080334, filed Oct. 28, 2015, which claims priority fromJapanese Patent Application No. 2014-221134, filed on Oct. 30, 2014. Thedisclosure of the foregoing application is hereby incorporated byreference in its entirety.

BACKGROUND

The present disclosure relates to a balloon catheter.

In treatments such as PTA (percutaneous transluminal angioplasty) andPTCA (percutaneous transluminal coronary angioplasty), a ballooncatheter is used. The balloon catheter is provided with a catheter shaftand a balloon. The balloon is provided on a distal end side of thecatheter shaft. A user of the balloon catheter introduces the ballooninto a constricted section or a blocked section that has occurred in ablood vessel, and dilates (inflates) the balloon, thus treating theconstricted or blocked section.

The catheter shaft is provided with an outer shaft and an inner shaft.The inner shaft is inserted inside the outer shaft. A base end portionof the balloon is joined to a leading end portion of the outer shaft.The balloon catheter is configured such that the balloon inflates ordeflates as a result of a compressed fluid flowing through a lumen ofthe outer shaft.

A leading end portion of the inner shaft extends further to the leadingend side than a leading end of the outer shaft. The portion of the innershaft that extends from the leading end of the outer shaft is covered bythe balloon. The leading end portion of the inner shaft is joined to aleading end portion of the balloon. A base end portion of the innershaft is joined to a partway position or the like of the outer shaft.

SUMMARY

When the balloon inflates, it is conceivable that an extending(expanding) force acts not only in a radial direction but also in anaxial line direction. As described above, the base end portion of theballoon is joined to the outer shaft. Thus, when the force that extendsin the axial line direction acts on the balloon, the balloon tries toextend toward the leading end side with respect to the outer shaft.Meanwhile, the leading end portion of the balloon is joined to the innershaft. Then, the base end portion of the inner shaft is joined to theouter shaft and so on. As a result, even when the balloon tries toextend toward the leading end side, displacement of the leading endportion of the balloon toward the leading end side is restricted by theinner shaft. It is therefore supposed that, in accordance with theinflation of the balloon, the balloon becomes warped into a bananashape. In this case, it is feared that a problem such as damage to theblood vessel may occur due to the warping of the balloon.

Various embodiments of the broad principles derived herein provide aballoon catheter capable of suppressing warping of a balloon.

Embodiments provide a balloon catheter that includes an outer shaft, aninner shaft, and an inflatable balloon. The inner shaft is insertedinside the outer shaft. A part of the inner shaft extends from a leadingend of the outer shaft. The balloon includes a base end side jointportion joined to the outer shaft and a leading end side joint portionjoined to the inner shaft. The inner shaft has an extension portionconfigured to extend in an axial line direction. The extension portionis provided further to a base end side than the leading end side jointportion.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will be described below in detail with reference to theaccompanying drawings in which:

FIG. 1 is an overall side view showing a configuration of a ballooncatheter;

FIG. 2A is a vertical cross section showing the configuration of theballoon catheter, and FIG. 2B is a cross-sectional view along a line A-Ashown in FIG.

1;

FIG. 3A and FIG. 3B are vertical cross sections illustrating operationsof a coil portion, where FIG. 3A shows a deflated state of a balloon andFIG. 3B shows an inflated state of the balloon; and

FIG. 4A and FIG. 4B are a front view showing another embodiment of anextendable/retractable portion.

DETAILED DESCRIPTION

Hereinafter, an embodiment will be explained with reference to thedrawings. FIG. 1 is an overall side view showing a configuration of aballoon catheter. FIG. 2A is a vertical cross section showing theconfiguration of the balloon catheter, and FIG. 2B is a cross-sectionalview along a line A-A shown in FIG. 1. Note that in FIG. 2A and FIG. 2B,a balloon is shown in an inflated state.

As shown in FIG. 1 and FIG. 2A, a balloon catheter 10 is provided withan outer shaft 11, an inner shaft 12, and a balloon 14. The inner shaft12 is inserted inside the outer shaft 11. Further, a hub 13 is attachedto a base end portion (a proximal portion) of the outer shaft 11 and theinner shaft 12. The balloon 14 is attached to a leading end side (adistal end side) of the outer shaft 11 and the inner shaft 12.

The outer shaft 11 is a flexible tubular member. The outer shaft 11 isformed of a resin material, and is, for example, formed of a polyamideelastomer. A lumen 11 a is formed in the outer shaft 11 and extendsalong the whole area of the outer shaft 11 in the axial line direction.The lumen 11 a is a through hole that extends in the axial linedirection of the outer shaft 11. The lumen 11 a communicates with theinterior of the balloon 14 and also communicates with the interior ofthe hub 13.

The outer shaft 11 includes an expanded diameter portion 16. Theexpanded diameter portion 16 is a portion whose inner diameter and outerdiameter are larger than the inner diameter and outer diameter of aportion further to the leading end side than the expanded diameterportion 16. The expanded diameter portion 16 is formed in the outershaft 11 over a predetermined range that includes the base end portionof the outer shaft 11. Specifically, the expanded diameter portion 16 isformed over a range from the base end portion of the outer shaft 11 to aposition on the leading end side separated from the base end portion bya predetermined dimension L. The predetermined dimension L is 5 mm to300 mm, for example. Specifically, in the present embodiment, the outershaft 11 includes a small diameter portion and the expanded diameterportion 16. The leading end portion of the expanded diameter portion 16is a tapered portion whose outer diameter and inner diameter becomegradually smaller toward the leading end side. The small diameterportion is a section that extends to the leading end side from a leadingend of the expanded diameter portion 16. Specifically, the smalldiameter portion extends toward the leading end side from the leadingend of the tapered portion of the expanded diameter portion 16. Theinner diameter and the outer diameter of the small diameter portion areconstant in the axial line direction. The inner diameter and the outerdiameter of the expanded diameter portion 16 are, respectively, largerthan the inner diameter and the outer diameter of the small diameterportion. Note that the leading end portion of the expanded diameterportion 16 need not necessarily be the tapered portion. The leading endportion of the expanded diameter portion 16 may be, for example, acurved portion whose diameter becomes smaller toward the leading endside.

It should be noted that the outer shaft 11 need not necessarily beformed of the same material across the whole area in the axial linedirection. For example, the outer shaft 11 may be formed by a pluralityof tubes formed from different materials being connected in the axialline direction. In this case, of the plurality of tubes configuring theouter shaft 11, it is conceivable that a tube positioned on the base endside be formed of a metal material having a relatively high rigidity,and a tube positioned on the leading end side be formed of the resinmaterial (the polyamide elastomer) having a relatively low rigidity.

The inner shaft 12 has a core wire 18 and a leading end tip 19. Theleading end tip 19 is joined to the leading end side of the core wire18. The core wire 18 is formed of a metal wire. The core wire 18 is, forexample, formed of a stainless steel wire. A wire 18 a that configuresthe core wire 18 has a circular shape in a transverse cross section. Thetransverse cross section is a cross section perpendicular to the axialline direction of the core wire 18. A leading end portion of the corewire 18 is tapered toward the leading end. Apart from the leading endportion, the outer diameter of the core wire 18 is substantiallyconstant along the whole area in the axial line direction. The outerdiameter of the core wire 18 (the wire 18 a) is smaller than the innerdiameter of the outer shaft 11. More specifically, the outer diameter ofthe core wire 18 is smaller than the inner diameter of the section tothe leading end side of the expanded diameter portion 16 in the outershaft 11. Thus, a predetermined gap is formed between an outerperipheral surface of the core wire 18 and in inner peripheral surfaceof the outer shaft 11. Further, the base end portion of the core wire 18is fixed to the hub 13.

Note that the core wire 18 may be formed of a material other than thestainless steel. The core wire 18 may be formed, for example, of asuperelastic alloy, such as a nickel titanium alloy or the like.Further, the core wire 18 may be formed such that the outer diameterbecomes smaller, in a stepped manner or in a continuous manner, from thebase end side toward the leading end side.

The leading end tip 19 is formed of a pliable resin material. A holeportion 25 that is open toward the base end side is formed in theleading end tip 19. The leading end portion of the core wire 18 isinserted into the hole portion 25. In a state in which the leading endportion of the core wire 18 is inserted into the hole portion 25, theleading end tip 19 and the core wire 18 are joined together andintegrated.

A part of the inner shaft 12 extends further to the leading end sidethan the leading end of the outer shaft 11. The balloon 14 is providedsuch that it covers, from the outside, the area of the inner shaft 12extending from the leading end of the outer shaft 11. The balloon 14 isformed of a thermoplastic polyamide elastomer. However, the balloon 14may be formed of another thermoplastic resin, such as polyethylene,polypropylene, or the like.

The balloon 14 has a base end side joint portion 21, a leading end sidejoint portion 22, and an inflation portion 23. The base end side jointportion 21 is a base end side portion of the balloon 14, and is theportion that is joined to the leading end portion of the outer shaft 11.The leading end side joint portion 22 is a leading end side portion ofthe balloon 14 and is the portion that is joined to the leading endportion of the inner shaft 12. The base end side joint portion 21 andthe leading end side joint portion 22 are, respectively, cylindricalportions that extend from the inflation portion 23. The leading endportion of the outer shaft 11 is inserted into the base end side jointportion 21. In a state in which the leading end portion of the outershaft 11 is inserted into the base end side joint portion 21, the baseend side joint portion 21 and the outer shaft 11 are joined together.Further, the inner shaft 12 is inserted into the leading end side jointportion 22. Specifically, the leading end side joint portion 22 isdisposed such that it covers a joint portion between the core wire 18and the leading end tip 19 in the inner shaft 12. In the presentembodiment, the leading end side joint portion 22, the leading end tip19, and the core wire 18 are overlapped with each other in the radialdirection. In this state, the leading end side joint portion 22, theleading end tip 19, and the core wire 18 are joined together by thermalwelding. In addition, in this joined state, a base end portion of theleading end tip 19 is substantially in the same position as the base endportion of the leading end side joint portion 22.

The inflation portion 23 is positioned between the base end side jointportion 21 and the leading end side joint portion 22, and is configuredto inflate or deflate. The inflation portion 23 has a cylindricalportion 23 a and a pair of tapered portions 23 b and 23 c. When theballoon 14 is inflated, the cylindrical portion 23 a is a portion of theballoon 14 whose diameter is substantially constant in the axial linedirection. The tapered portion 23 b extends toward the base end sidefrom a base end of the cylindrical portion 23 a. The tapered portion 23c extends toward the leading end side from a leading end of thecylindrical portion 23 a. The cylindrical portion 23 a is a portion overwhich the outer diameter of the inflation portion 23 (the balloon 14)becomes largest. The outer diameter of each of the pair of taperedportions 23 b and 23 c becomes gradually smaller the further from thecylindrical portion 23 a.

The interior of the balloon 14 is communicated with the hub 13 via thelumen 11 a of the outer shaft 11. In this way, a compressed fluid thatis supplied via the hub 13 is supplied to the interior of the balloon 14via the lumen 11 a of the outer shaft 11. Thus, the lumen 11 a functionsas a fluid lumen to cause the compressed fluid to flow. When thecompressed fluid is supplied to the interior of the balloon 14 via thelumen 11 a of the outer shaft 11, the balloon 14 enters an inflatedstate. The inflated state is a state in which the balloon 14 has beeninflated. On the other hand, when a negative pressure is applied to thelumen 11 a and the compressed fluid is discharged from the interior ofthe balloon 14, the balloon 14 enters a deflated state. The deflatedstate is a state in which the balloon 14 has been deflated.

The balloon 14 is formed as a multi-wing type that has a plurality ofwings in a circumferential direction. In the present embodiment, theballoon 14 is formed as a three-wing type. When the balloon 14 is in thedeflated state, the inflation portion 23 is folded over so as to formthe plurality of wings. Specifically, in the deflated state, the foldedover plurality of wings are wound around the axis of the inner shaft 12.

The leading end portion of the inner shaft 12 extends further to theleading end side than the balloon 14. A guide wire lumen 27, throughwhich a guide wire G can be inserted, is formed in the portion of theinner shaft 12 extending further to the leading end side than theballoon 14. The guide wire lumen 27 is formed in the leading end tip 19.Specifically, the guide wire lumen 27 is formed, in the leading end tip19, further to the leading end side than the core wire 18. The guidewire lumen 27 is formed so as to extend in the axial line direction. Aleading end opening 27 a of the guide wire lumen 27 opens in a leadingend surface of the leading end tip 19. A base end opening 27 b of theguide wire lumen 27 opens in an outer peripheral surface 19a of theleading end tip 19. The base end opening 27 b opens toward the outerside in the radial direction of the leading end tip 19. The radialdirection is a direction orthogonal to the axial line direction. Theouter side in the radial direction is a side separated from an axialcenter of the balloon catheter 10.

The guide wire G can be introduced into the guide wire lumen 27 via theleading end opening 27 a, and can be drawn out to the base end side fromthe guide wire lumen 27 via the base end opening 27 b. The guide wire Gthat has been drawn out from the guide wire lumen 27 is disposed alongthe axial line direction on the outer peripheral surface of the balloon14, on the same side, in the circumferential direction, as the side onwhich the base end opening 27 b opens (refer to FIG. 2B).

Two contrast rings 29 are attached to the portion of the inner shaft 12(more specifically, of the core wire 18) that is covered by the balloon14. One of the contrast rings 29 is attached in a position correspondingto a boundary portion between the base end side joint portion 21 and theinflation portion 23. The other contrast ring 29 is attached to aposition corresponding to a boundary portion between the leading endside joint portion 22 and the inflation portion 23. The contrast rings29 improve visibility of the position of the balloon 14 under X-rayprojection, and make it easier to determine the position of the balloon14 with respect to a targeted treatment location.

A plurality of (specifically, three) elements 31 are provided on theouter peripheral side of the balloon 14. Each of the plurality ofelements 31 is formed as an elongate member made of an elastic resinmaterial, and is specifically formed of a polyamide resin. A transversecross section shape of the element 31 is triangular. The transversecross section is a face that is perpendicular to the axial linedirection of the element 31. Each of the elements 31 is arranged suchthat one edge of the triangular shape of the element 31 is positioned onthe outer peripheral surface of the balloon 14, and one corner of thetriangular shape protrudes outward from the outer peripheral surface ofthe balloon 14. Note that the transverse cross section shape of each ofthe elements 31 need not necessarily be triangular. The transverse crosssection shape of each of the elements 31 may be circular, square, or soon. Further, the transverse cross section shape of each of the elements31 may differ between each of the elements 31.

Each of the elements 31 is provided such that it extends across theballoon 14 in the axial line direction. A base end portion of each ofthe elements 31 is mounted on the outer shaft 11 via a first mountingmember 32. A leading end portion of each of the elements 31 is mountedon the inner shaft 12 via a second mounting member 33. The firstmounting member 32 is a cylindrical member surrounding the outer shaft11. The first mounting member 32 is formed of a resin material. Thefirst mounting member 32 is positioned further to the base end side thanthe base end side joint portion 21 of the balloon 14, and is joined tothe outer shaft 11 in a position adjacent to the balloon 14. The firstmounting member 32 is joined to the outer peripheral surface of theouter shaft 11 by thermal welding. Further, the base end portion of eachof the elements 31 is joined to the outer peripheral surface of thefirst mounting member 32 by thermal welding.

Note that the first mounting member 32 may be movably provided withrespect to the outer shaft 11 and need not necessarily be joined (fixed)to the outer shaft 11.

The second mounting member 33 is a cylindrical member that surrounds theinner shaft 12. The second mounting member 33 is formed of a resinmaterial. The second mounting member 33 is positioned further to theleading end side than the leading end side joint portion 22 of theballoon 14, and is joined to the inner shaft 12 in a position adjacentto the balloon 14. Only the leading end side of the second mountingmember 33 is joined to the outer peripheral surface of the inner shaft12, and the base end side of the second mounting member 33 is separatedfrom the outer peripheral surface of the inner shaft 12. Specifically,the second mounting member 33 is joined to the leading end tip 19. Then,the leading end portion of each of the elements 31 is joined by thermalwelding to the inside surface on the base end side of the secondmounting member 33. In this way, each of the plurality of elements 31includes the base end portion joined to the outer shaft 11, and theleading end portion joined to an extending portion of the inner shaft 12that extends further to the leading end side than the leading end sidejoint portion 22 of the balloon 14.

As shown in FIG. 2B, the three elements 31 are arranged at predeterminedintervals along the circumferential direction of the balloon 14. Thecircumferential direction is a direction along the balloon 14 in thetransverse cross section. Specifically, an element 31 a and an element31 c are arranged at a 90 degree interval in the circumferentialdirection of the balloon 14. An element 31 b and the element 31 c arearranged at a 90 degree interval in the circumferential direction of theballoon 14. The element 31 a and the element 31 b are arranged at a 180degree interval in the circumferential direction. The two elements 31 aand 31 b are arranged on the balloon 14 such that they are on eitherside of a section whose position in the circumferential direction on theballoon 14 is the same position as the base end opening 27 b.Hereinafter, the section whose position in the circumferential directionon the balloon 14 is the same position as the base end opening 27 b isreferred to as an opening side section 39. The opening side section 39is positioned in a central portion between the two elements 31 a and 31b. Thus, of the elements 31 a, 31 b, and 31 c arranged on the balloon14, an interval between the two elements 31 a and 31 b that arepositioned in the circumferential direction so as to be on either sideof the opening side section 39 is larger than an interval between thetwo elements 31 a and 31 c (31 b and 31 c) that are adjacent to eachother in the circumferential direction without being on either side ofthe opening side section 39.

In the opening side section 39 on the balloon 14, the guide wire G isinstalled so as to extend across the balloon 14 in the axial linedirection. In this case, the guide wire G is installed between the twoelements 31 a and 31 b that are adjacent to each other with the largerinterval therebetween. Specifically, the guide wire G is installed inthe central portion between the two elements 31 a and 31 b. Thus, theballoon catheter 10 is configured such that each of the elements 31 a to31 c and the guide wire G are arranged at 90 degree intervals (equalintervals) in the circumferential direction on the outer peripheralsurface of the balloon 14.

By arranging each of the elements 31 a to 31 c on the balloon 14 asdescribed above, interference between the elements 31 a to 31 c and theguide wire G on the balloon 14 may be inhibited. Note that thearrangement interval and the number of the elements 31 on the balloon 14are not necessarily limited to the examples described above, and thearrangement interval and the number may be chosen as desired.

The balloon catheter 10 is provided with an extendable/retractableportion that is extendable/retractable in the axial line direction. Morespecifically, the inner shaft 12 has the extendable/retractable portion.The configuration of the extendable/retractable portion will beexplained below.

As shown in FIG. 2A, the inner shaft 12 has the core wire 18. The corewire 18 has a coil portion 35. The coil portion 35 is a portion of thewire 18 a, which configures the wire 18, that is wound in a spiral shape(coil shape) along the axial line direction of the inner shaft 12. Thecoil portion 35 is extendable/retractable in the axial line direction asa result of elastic deformation. Below, a state of the extended coilportion 35 is referred to as an extended state. A state of the retractedcoil portion 35 is referred to as a retracted state. FIG. 2A shows thecoil portion 35 in the extended state. FIG. 3A that will be describedlater shows the coil portion 35 in the retracted state.

The coil portion 35 is formed by the tight winding (compact winding) ofthe wire 18 a configuring the core wire 18. More specifically, when in anatural state in which a tensile force in the axial line direction isnot imparted to the coil portion 35, the coil portion 35 is in a tightlycoiled state (refer to FIG. 3A). The tightly coiled state is a state inwhich, in the coil portion 35, sections of the wire 18 a adjacent toeach other in the axial line direction are in contact (close contact)with each other.

Note that the coil portion 35 need not necessarily be in the tightlycoiled state when in the natural state. The coil portion 35 may be in aroughly coiled state when in the natural state. The roughly coiled stateis a state in which there are gaps between the sections of the wire 18 aadjacent to each other in the axial line direction.

The coil portion 35 is arranged inside the expanded diameter portion 16(the lumen 11 a) of the outer shaft 11. Specifically, the coil portion35 is arranged on the leading end side in the expanded diameter portion16. More specifically, the coil portion 35 is arranged in the vicinityof the leading end portion of the expanded diameter portion 16. An outerdiameter D1 (refer to FIG. 3A) of the coil portion 35 is larger than aninner diameter D2 of an area of the outer shaft 11 further to theleading end side than the expanded diameter portion 16 (D1>D2). Further,the outer diameter D1 (coil diameter) of the coil portion 35 is smallerthan an inner diameter D3 of the expanded diameter portion 16 (D1<D3).Thus, when the coil portion 35 is arranged inside the expanded diameterportion 16, a predetermined gap 37 is formed between the outerperipheral surface of the coil portion 35 and the inner peripheralsurface of the expanded diameter portion 16. In a section of theexpanded diameter portion 16 in which the coil portion 35 is arranged,the fluid flows through the gap 37 and the inside of the coil portion35.

An operation of the coil portion 35 will be explained with reference toFIG. 3. FIG. 3A and FIG. 3B are vertical cross sections illustrating theoperation of the coil portion 35. FIG. 3A shows the deflated state ofthe balloon 14. FIG. 3B shows the inflated state of the balloon 14.

As shown in FIG. 3A, when the balloon 14 is in the deflated state, thecoil portion 35 is in the natural state, namely, is in the retractedstate (contracted state). In this case, a length of the balloon 14 inthe axial line direction is a length L1, and a length of the coilportion 35 in the axial line direction is a length L2.

As shown in FIG. 3B, when the compressed fluid is introduced into theballoon 14, the balloon 14 enters into the inflated state. When theballoon 14 inflates, in addition to expanding in the radial direction,the balloon 14 expands (extends) in the axial line direction. In thiscase, the balloon 14 extends in the axial line direction by ΔL, and thelength in the axial line direction becomes L3 (L3−L1=ΔL).

Specifically, when the balloon 14 inflates, the balloon 14 extends by ΔLtoward the leading end side with respect to the outer shaft 11 in theaxial line direction. Then, in accordance with the extension of theballoon 14, the inner shaft 12 (the core wire 18) that is joined to theleading end portion of the balloon 14 is pulled to the leading end sideby the balloon 14. When the inner shaft 12 is pulled to the leading endside, the coil portion 35 of the core wire 18 extends in the axial linedirection. Specifically, the coil portion 35 extends by the same lengthas the extension amount ΔL of the balloon 14 in the axial linedirection. As a result, the length of the coil portion 35 in the axialline direction becomes a length L4 (L4−L2=ΔL). In other words, in thiscase, when the coil portion 35 extends in the axial line direction, theinner shaft 12 is displaced toward the leading end side by the extensionamount ΔL of the balloon 14 in the axial line direction. In this way,the occurrence of warping of the balloon 14 may be suppressed.

After that, when the compressed fluid is discharged from the balloon 14,the balloon 14 enters into the deflated state. When the balloon 14 is inthe deflated state, the tensile force that was acting on the coilportion 35 in the axial line direction due to the balloon 14 is nolonger present. The coil portion 35 contracts in the axial linedirection due to its own elasticity (return elasticity). As a result,the coil portion 35 returns to the natural state and the length thereofin the axial line direction returns to the original length L2. In otherwords, the length of the coil portion 35 returns to the length L2 beforethe balloon inflation. Further, since the length of the coil portion 35returns to the original length L2, the length of the balloon 14 in theaxial line direction also returns to the original length L1. Thus, inthis case, the balloon 14 returns to the original (pre-inflation)deflated state (the state shown in FIG. 3A).

Next, a method of use of the balloon catheter 10 will be brieflyexplained.

A user inserts a guiding catheter through a sheath introducer that hasfirst been inserted into a blood vessel, and introduces a leading endopening portion of the guiding catheter as far as a coronary arteryentry portion. Next, the user inserts the guide wire G through theguiding catheter and introduces the inserted guide wire G from thecoronary artery entry portion as far as a peripheral portion via aportion to be treated, such as a constricted portion.

Next, the user introduces the balloon catheter 10 into the guidingcatheter along with the guide wire G. When introducing the ballooncatheter 10, of the outer shaft 11, only a section further to theleading end side than the expanded diameter portion 16 is introducedinto the guiding catheter, and the expanded diameter portion 16 is thusnot introduced into the guiding catheter (namely, is not introduced intothe body). After the balloon catheter 10 has been introduced into theguiding catheter, the balloon 14 is arranged at the portion to betreated while applying a push and pull maneuver.

Next, the user supplies the compressed fluid to the balloon 14 via thelumen 11 a of the outer shaft 11, from the hub 13 side, using apressurizer. In this way, the balloon 14 is inflated. When the balloon14 inflates, the constricted portion is expanded. Further, in accordancewith the inflation of the balloon 14, the respective elements 31arranged on the outer peripheral side of the balloon 14 are pressedagainst the blood vessel wall by the balloon 14, and bite into the bloodvessel wall. In this way, the balloon 14 may be inhibited from slippingfrom the constricted portion.

As described above, when the balloon 14 is inflated, the occurrence ofwarping of the balloon 14 is suppressed by the operation of the coilportion 35. It is thus possible to avoid occurrence of a situation inwhich the respective elements 31 are not arranged at the predeterminedintervals around the balloon 14, such as becoming concentrated, on theouter peripheral side of the balloon 14, on the opposite side to a sideon which the balloon 14 is warping. As a result, each of the elements 31may favorably function in being able to stop the slipping of the balloon14.

After the user finishes expanding the constricted portion using theballoon 14, the user discharges the compressed fluid from the balloon 14and causes the balloon 14 to be in the deflated state. Then, the userpulls out the balloon 14 in the deflated state, namely, the ballooncatheter 10, from the body. Since the balloon 14 returns to the original(pre-inflation) deflated state by being once more deflated, as describedabove, in this case, it is possible to suppress a deterioration inoperability when pulling out the balloon 14.

According to the configuration of the present embodiment described indetail above, the following effects may be obtained.

The coil portion 35 is formed by winding the wire 18 a, which configuresthe core wire 18, in the spiral shape in the axial line direction. Then,the extendable/retractable portion is configured that isextendable/retractable in the axial line direction by the coil portion35. In this case, in comparison to a case in which theextendable/retractable portion is formed of a highly pliable material(such as a rubber material), the extendable/retractable portion may beformed while inhibiting a significant deterioration in rigidity.

A dimension in the radial direction of the coil portion 35 is largerthan that of other portions of the coil wire 18. Thus, when the coilportion 35 is arranged inside the balloon 14, a balloon diameterincreases at the time of the deflation of the balloon 14, and there is arisk that passability of the balloon 14 inside the body may deteriorate.With respect to this point, the coil portion 35 is arranged further tothe base end side than the balloon 14, and thus, the warping of theballoon 14 may be suppressed while inhibiting the deterioration in thepassability of the balloon 14.

A portion on the base end side of the outer shaft 11 has the expandeddiameter portion 16 that has an expanded diameter compared to theleading end side thereof. The coil portion 35 is arranged inside theexpanded diameter portion 16. In this case, the coil portion 35 whosedimension in the radial direction is large may be arranged inside theouter shaft 11. Further, since the expanded diameter portion 16 isprovided on the base end side of the outer shaft 11, it is possible notto introduce the expanded diameter portion 16 into the body when theouter shaft 11 is introduced into the body. In this way, the coilportion 35 may be arranged inside the outer shaft 11 while inhibiting adeterioration in the insertability of the outer shaft 11.

The coil portion 35 is positioned on the leading end side in theexpanded diameter portion 16. Thus, a configuration is obtained in whichthe coil portion 35 is arranged in the expanded diameter portion 16, anda length of the portion of the core wire 18 further to the leading endside than the coil portion 35 may be made shorter. In this way, when theabove-described leading end side portion is displaced in the axial linedirection in accordance with the extension and retraction of the coilportion 35, it is possible to reduce resistance when the leading endside portion slides along the inner peripheral surface of the outershaft 11. As a result, even with this configuration, the extension andretraction functions of the coil portion 35 may be favorably exhibited.

The present disclosure is not limited to the above-described embodiment,and may be performed in the following manner, for example.

(1) In the above-described embodiment, a part of the core wire 18 isused to form the coil portion 35. However, the coil portion may formedseparately from a core wire. For example, as shown in an example in FIG.4A, a core wire 41 has a plurality of wire portions 42 and 43 that aredivided partway along the axial line direction. In the example shown inFIG. 4A, the core wire 41 has two wire portions 42 and 43. A coil spring44, which is formed separately from the core wire 41 (the wire portions42 and 43), is provided between the two wire portions 42 and 43. One endof the coil spring 44 is attached to a base end of the wire portion 42.The other end of the coil spring 44 is attached to a leading end of thewire portion 43.

The coil spring 44 is formed by winding a metal (stainless steel, forexample) wire in a spiral shape in the axial line direction of acatheter. Hook portions 44 a and 44 b are respectively provided on bothend portions of the coil spring 44. Meanwhile, hook portions 42 a and 43a are respectively provided on end portions, of each of the wireportions 42 and 43, on the coil spring 44 side. The hook portion 42 a ofthe wire portion 42 is hooked onto the hook portion 44 a of the coilspring 44, and the hook portion 43 a of the wire portion 43 is hookedonto the hook portion 44 b of the coil spring 44. In this way, the coilspring 44 is attached to each of the wire portions 42 and 43,respectively.

According to this configuration, since the coil spring 44 is formedseparately from the core wire 41, freedom of design of the coil portionmay be enhanced. Thus, the coil portion may be favorably designed inaccordance with the specifications (the size and shape, inflationpressure and the like) of the balloon 14. Note that, in this case, aninner shaft is configured including the coil spring 44 and the core wire41.

(2) In the above-described embodiment, the coil portion 35 is providedas the extendable/retractable portion that is configured to extend andretract in the axial line direction as a result of elastic deformation.However, the extendable/retractable portion need not necessarily be thecoil portion 35. For example, as shown in FIG. 4B, a resin tube 46formed of an elastic resin material (a rubber material, for example) maybe used as the extendable/retractable portion. The resin tube 46 isconfigured to be extendable and retractable in the axial line directionas a result of elastic deformation. In the example shown in FIG. 4B,similarly to the above-described example shown in FIG. 4A, the core wire41 has the plurality of wire portions 42 and 43 divided in the axialline direction, and the resin tube 46 is provided between the wireportions 42 and 43. The base end portion of the wire portion 42 isinserted into the leading end side of the resin tube 46. In a state inwhich the wire portion 42 is inserted into the resin tube 46, the resintube 46 and the wire portion 42 are joined together by bonding. Further,the leading end portion of the wire portion 43 is inserted into the baseend side of the resin tube 46. In a state in which the wire portion 43is inserted into the resin tube 46, the resin tube 46 and the wireportion 43 are joined together by bonding. In other words, in this case,the two wire portions 42 and 43 are connected via the resin tube 46.

With this configuration also, the resin tube 46 is configured to extendand retract in the axial line direction as a result of elasticdeformation, and thus, the resin tube 46 is used as theextendable/retractable portion. Further, the resin tube 46 differs fromthe coil portion 35 and the coil spring 44 in that the dimension thereofin the radial direction does not become particularly large. In thiscase, the coil portion (the resin tube 46) may be arranged inside theouter shaft 11 without providing the expanded diameter portion 16 on theouter shaft 11. It should be noted that, in this case, an inner shaft isconfigured so as to include the core wire 41 and the resin tube 46.

(3) In the above-described embodiment, the coil portion 35 is providedas the extendable/retractable portion that is configured to extend andretract as a result of elastic deformation. However, theextendable/retractable portion need not necessarily be extendable andretractable as a result of elastic deformation. For example, a waveformportion may be used as the extendable/retractable portion. The waveformportion is a portion in which a part of a core wire (a wire) is formedin a wave shape (zigzag shape) along the axial line direction. Thewaveform portion is configured such that it is foldable and expandablein the axial line direction as a result of an external force beingapplied in the axial line direction. When the waveform portion isfolded, it becomes shorter in the axial line direction, and when itexpands, it becomes longer in the axial line direction. In other words,the waveform portion is extendable and retractable in the axial linedirection. Thus, the waveform portion may be used as theextendable/retractable portion.

(4) The core wire 18 may have an extension portion that is configured toonly extend in the axial line direction, in place of the coil portion 35(the extendable/retractable portion) that is extendable and retractablein the axial line direction. The extension portion is formed of aplastically deformable material, for example, and extends in the axialline direction as a result of plastic deformation when a tensile forceis applied in the axial line direction. Further, when the extensionportion is once caused to be in an extended state, the extended state iscontinuously maintained. With this configuration also, when the balloon14 extends in the axial line direction, the inner shaft 12 is pulledfurther to the leading end side than the balloon 14, and the extensionportion extends in the axial line direction. In other words, in thiscase also, since the joint portion between the inner shaft 12 and theballoon 14 is displaced to the leading end side by the extension portionextending, the occurrence of warping of the balloon 14 may besuppressed.

(5) In the above-described embodiment, the coil portion 35 is arrangedon the leading end side in the expanded diameter portion 16 of the outershaft 11. However, the coil portion 35 may be arranged on the base endside in the expanded diameter portion 16. Further, the coil portion 35may be arranged further to the leading end side than the expandeddiameter portion 16, in the outer shaft 11. In this case, it issufficient that the outer diameter of the coil portion 35 be smallerthan the inner diameter of the outer shaft 11 at a portion further tothe leading end side than the expanded diameter portion 16. Further, thecoil portion 35 may be provided inside the balloon 14. In this case, thesize of the coil portion 35 may be set while taking into considerationthe outer diameter of the balloon 14 when the balloon 14 is deflated.Even in this case, the coil portion 35 is positioned further to the baseend side than the leading end side joint portion 22 of the balloon 14.Thus, by the inner shaft 12 being pulled to the leading end side inaccordance with the inflation of the balloon 14, the coil portion 35extends in the axial line direction. The warping of the balloon 14 issuppressed by the coil portion 35 extending.

(6) In the above-described embodiment, the core wire 18 has the singlecoil portion 35. However, the core wire 18 may have a plurality of thecoil portions 35 arranged at predetermined intervals in the axial linedirection.

(7) In the above-described embodiment, the solid core wire 18 is used asa part of the inner shaft 12. However, a hollow tube may be used inplace of the core wire 18. Then, a coil portion may be formed using thehollow tube.

(8) In the above-described embodiment, the elements 31 are provided onthe outer peripheral side of the balloon 14. However, the elements 31need not necessarily be provided on the outer peripheral side of theballoon 14. Specifically, the balloon catheter 10 need not necessarilybe provided with the elements 31. Further, in the above-describedembodiment, the plurality of elements 31 are provided. However, a numberof the elements 31 may be one.

(9) In the above-described embodiment, the balloon catheter 10 used forthe treatment of a coronary artery is exemplified. However, thetechnical features disclosed in the above-described embodiment may beapplied to a balloon catheter used in other blood vessels, such as afemoral artery or a pulmonary artery, or alternatively, in a urinarytract or gastrointestinal tract or other in vivo “tubes” and “cavities.”

(10) In the above-described embodiment, the inner shaft 12 has the corewire 18 and the leading end tip 19. However, the inner shaft 12 need notnecessarily be provided with the leading end tip 19. For example, theinner shaft 12 may be configured by a single core wire. In this case, itis sufficient that the core wire be a hollow member, for example, and bea member in which a guide wire lumen 27 is formed in a portion thatprotrudes further to the leading end side than the leading end of theballoon 14. In this case, the core wire may include a configurationcorresponding to the extension portion, such as the coil portion 35, theresin tube 46 or the like.

(11) In the above-described embodiment, the base end opening 27 b thatis a guide wire opening is positioned further to the leading end sidethan the leading end of the balloon 14. However, the guide wire openingmay be positioned further to the base end side than the base end of theballoon 14. In this case, for example, the inner shaft 12 may beprovided with the core wire 18, a hollow tube, and the leading end tip19 in that order from the base end side. In this case, it is sufficientthat the leading end of the core wire 18 be positioned further to thebase end side than the base end of the balloon 14, and that the hollowtube be joined to the leading end side of the core wire 18. Then, theguide wire opening may be formed in the hollow tube in a positionpartway along the axial line direction.

(12) In the above-described embodiment, the base end portion of theleading end tip 19 is in substantially the same position as the base endportion of the leading end side joint portion 22 of the balloon 14.However, the base end portion of the leading end tip 19 may be in adifferent position to the base end portion of the leading end side jointportion 22. For example, the base end portion of the leading end tip 19may be positioned further to the base end side than the base end sidejoint portion 21 of the balloon 14. In this case, it is sufficient thatthe leading end tip 19 be a hollow member that extends inside theballoon 14. Further, in this case, it is sufficient that the guide wirelumen 27 be configured such that openings respectively formed in theouter peripheral surface of the outer shaft 11 and in the outerperipheral surface of the leading end tip 19 communicate with eachother.

(13) In the above-described embodiment, the outer shaft 11 includes theexpanded diameter portion 16. However, the outer shaft 11 need notnecessarily include the expanded diameter portion 16. In this case, forexample, the outer shaft 11 may be a cylindrical member whose innerdiameter and outer diameter are substantially constant in the axial linedirection. Further, the outer shaft 11 may be configured such that theinner diameter is substantially constant in the axial line directionwhile the outer diameter changes in the axial line direction. Further,the outer shaft 11 may be a tubular member whose outer diameter changesat a predetermined position in the axial line direction.

(14) In the above-described embodiment, the plurality of elements 31 arejoined to the outer shaft 11 and the inner shaft 12 via the firstmounting member 32 and the second mounting member 33. However, theballoon catheter 10 need not necessarily be provided with the firstmounting member 32 and the second mounting member 33. For example, theplurality of elements 31 may be directly joined to the outer shaft 11and the inner shaft 12. Further, the balloon catheter 10 may be providedwith only one of the first mounting member 32 and the second mountingmember 33.

(15) In the above-described embodiment, the leading end portions of theplurality of elements 31 are joined to the leading end tip 19. However,the leading end portions of the plurality of elements 31 may be joinedto the core wire 18.

The apparatus and methods described above with reference to the variousembodiments are merely examples. It goes without saying that they arenot confined to the depicted embodiments. While various features havebeen described in conjunction with the examples outlined above, variousalternatives, modifications, variations, and/or improvements of thosefeatures and/or examples may be possible. Accordingly, the examples, asset forth above, are intended to be illustrative. Various changes may bemade without departing from the broad spirit and scope of the underlyingprinciples.

What is claimed is:
 1. A balloon catheter comprising: an outer shaft; aninner shaft inserted inside the outer shaft, a part of the inner shaftextending from a leading end of the outer shaft; and an inflatableballoon including a base end side joint portion joined to the outershaft and a leading end side joint portion joined to the inner shaft,wherein the inner shaft has an extension portion configured to extend inan axial line direction, the extension portion being provided further toa base end side than the leading end side joint portion.
 2. The ballooncatheter according to claim 1, wherein the extension portion is anextendable/retractable portion configured to extend and retract in theaxial line direction as a result of elastic deformation.
 3. The ballooncatheter according to claim 2, wherein the extendable/retractableportion is a coil portion formed by winding a wire configuring at leasta part of the inner shaft in a spiral shape in the axial line direction.4. The balloon catheter according to claim 1, wherein the extensionportion is arranged further to the base end side than the base end sidejoint portion.
 5. The balloon catheter according to claim 4, wherein theouter shaft has an expanded diameter portion that is a portionpositioned on the base end side and is a portion with an expandeddiameter compared to a portion on a leading end side, and the extensionportion is arranged inside the expanded diameter portion.
 6. The ballooncatheter according to claim 5, wherein the extension portion is arrangedon the leading end side in the expanded diameter portion.
 7. The ballooncatheter according to claim 1, further comprising: a plurality ofelongate members, each of the elongate members being provided on anouter peripheral side of the balloon and extending across the balloon inthe axial line direction, and being arranged at predetermined intervalsin a circumferential direction of the balloon, wherein each of theplurality of elongate members includes a base end portion joined to theouter shaft, and a leading end portion joined to an extending portionextending further to the leading end side than the leading end side joinportion of the balloon, in the inner shaft.
 8. The balloon catheteraccording to claim 7, wherein a lumen for a guide wire is formed in theextending portion, the lumen extending from a leading end to the baseend side, an opening of the base end side of the lumen opens in an outerperipheral surface of the extending portion, and when a section whoseposition in the circumferential direction on the outer peripheralsurface of the balloon is the same position as the opening is an openingside section, of the plurality of elongate members, an interval betweentwo of the elongate members adjacent to each other in thecircumferential direction on either side of the opening side section islarger than an interval between two of the elongate members adjacent toeach other in the circumferential direction without being on either sideof the opening side section.